Abnormalities of regional lung function associated with ventricular septal defect and pulmonary artery band.

Xenon-133 ventilation-perfusion scans and technetium-99m angiocardiograms were performed 47 times in 34 patients. All patients had ventricular septal defect (VSD), 17 with pulmonary artery band (PAB), 6 with isolated VSD, 4 with pulmonary valvar stenosis (PS), and 7 with transposition of the great arteries (d-TGA), VSD, and PAB. Patients with VSD had slightly depressed ventilation fraction of the left lung and slightly elevated perfusion fraction of the left lung, both before and after closure of the VSD. Patients with VSD and PAB had slightly depressed ventilation fraction of the left lung but perfusion fraction of the left lung that was either markedly elevated or markedly depressed. After closure of VSD and removal of PAB the perfusion abnormality returned toward normal in some patients but remained abnormal in most. The findings were similar in most patients with d-TGA. Ventilation-perfusion ratio was nearly normal in patients with VSD alone, both before and after closure of VSD. In patients with VSD with PAB the severe abnormality of ventilation-perfusion ratio returned toward normal after corrective operation but did not reach normal. There was no abnormality of distribution of perfusion along the cephalocaudal axis of the lung with the patient supine.